/*
** $Id: lmathlib.c,v 1.119.1.1 2017/04/19 17:20:42 roberto Exp $
** Standard mathematical library
** See Copyright Notice in lua.h
*/

#define lmathlib_c
#define LUA_LIB

#include "lprefix.h"

#include <stdlib.h>
#include <math.h>

#include "lua.h"

#include "lauxlib.h"
#include "lualib.h"

#undef PI
#define PI (l_mathop(3.141592653589793238462643383279502884))

#if !defined(l_rand) /* { */
#if defined(LUA_USE_POSIX)
#define l_rand() random()
#define l_srand(x) srandom(x)
#define L_RANDMAX 2147483647 /* (2^31 - 1), following POSIX */
#else
#define l_rand() rand()
#define l_srand(x) srand(x)
#define L_RANDMAX RAND_MAX
#endif
#endif /* } */

static int math_abs(lua_State *L)
{
  if (lua_isinteger(L, 1))
  {
    lua_Integer n = lua_tointeger(L, 1);
    if (n < 0)
      n = (lua_Integer)(0u - (lua_Unsigned)n);
    lua_pushinteger(L, n);
  }
  else
    lua_pushnumber(L, l_mathop(fabs)(luaL_checknumber(L, 1)));
  return 1;
}

static int math_sin(lua_State *L)
{
  lua_pushnumber(L, l_mathop(sin)(luaL_checknumber(L, 1)));
  return 1;
}

static int math_cos(lua_State *L)
{
  lua_pushnumber(L, l_mathop(cos)(luaL_checknumber(L, 1)));
  return 1;
}

static int math_tan(lua_State *L)
{
  lua_pushnumber(L, l_mathop(tan)(luaL_checknumber(L, 1)));
  return 1;
}

static int math_asin(lua_State *L)
{
  lua_pushnumber(L, l_mathop(asin)(luaL_checknumber(L, 1)));
  return 1;
}

static int math_acos(lua_State *L)
{
  lua_pushnumber(L, l_mathop(acos)(luaL_checknumber(L, 1)));
  return 1;
}

static int math_atan(lua_State *L)
{
  lua_Number y = luaL_checknumber(L, 1);
  lua_Number x = luaL_optnumber(L, 2, 1);
  lua_pushnumber(L, l_mathop(atan2)(y, x));
  return 1;
}

static int math_toint(lua_State *L)
{
  int valid;
  lua_Integer n = lua_tointegerx(L, 1, &valid);
  if (valid)
    lua_pushinteger(L, n);
  else
  {
    luaL_checkany(L, 1);
    lua_pushnil(L); /* value is not convertible to integer */
  }
  return 1;
}

static void pushnumint(lua_State *L, lua_Number d)
{
  lua_Integer n;
  if (lua_numbertointeger(d, &n)) /* does 'd' fit in an integer? */
    lua_pushinteger(L, n);        /* result is integer */
  else
    lua_pushnumber(L, d); /* result is float */
}

static int math_floor(lua_State *L)
{
  if (lua_isinteger(L, 1))
    lua_settop(L, 1); /* integer is its own floor */
  else
  {
    lua_Number d = l_mathop(floor)(luaL_checknumber(L, 1));
    pushnumint(L, d);
  }
  return 1;
}

static int math_ceil(lua_State *L)
{
  if (lua_isinteger(L, 1))
    lua_settop(L, 1); /* integer is its own ceil */
  else
  {
    lua_Number d = l_mathop(ceil)(luaL_checknumber(L, 1));
    pushnumint(L, d);
  }
  return 1;
}

static int math_fmod(lua_State *L)
{
  if (lua_isinteger(L, 1) && lua_isinteger(L, 2))
  {
    lua_Integer d = lua_tointeger(L, 2);
    if ((lua_Unsigned)d + 1u <= 1u)
    { /* special cases: -1 or 0 */
      luaL_argcheck(L, d != 0, 2, "zero");
      lua_pushinteger(L, 0); /* avoid overflow with 0x80000... / -1 */
    }
    else
      lua_pushinteger(L, lua_tointeger(L, 1) % d);
  }
  else
    lua_pushnumber(L, l_mathop(fmod)(luaL_checknumber(L, 1),
                                     luaL_checknumber(L, 2)));
  return 1;
}

/*
** next function does not use 'modf', avoiding problems with 'double*'
** (which is not compatible with 'float*') when lua_Number is not
** 'double'.
*/
static int math_modf(lua_State *L)
{
  if (lua_isinteger(L, 1))
  {
    lua_settop(L, 1);     /* number is its own integer part */
    lua_pushnumber(L, 0); /* no fractional part */
  }
  else
  {
    lua_Number n = luaL_checknumber(L, 1);
    /* integer part (rounds toward zero) */
    lua_Number ip = (n < 0) ? l_mathop(ceil)(n) : l_mathop(floor)(n);
    pushnumint(L, ip);
    /* fractional part (test needed for inf/-inf) */
    lua_pushnumber(L, (n == ip) ? l_mathop(0.0) : (n - ip));
  }
  return 2;
}

static int math_sqrt(lua_State *L)
{
  lua_pushnumber(L, l_mathop(sqrt)(luaL_checknumber(L, 1)));
  return 1;
}

static int math_ult(lua_State *L)
{
  lua_Integer a = luaL_checkinteger(L, 1);
  lua_Integer b = luaL_checkinteger(L, 2);
  lua_pushboolean(L, (lua_Unsigned)a < (lua_Unsigned)b);
  return 1;
}

static int math_log(lua_State *L)
{
  lua_Number x = luaL_checknumber(L, 1);
  lua_Number res;
  if (lua_isnoneornil(L, 2))
    res = l_mathop(log)(x);
  else
  {
    lua_Number base = luaL_checknumber(L, 2);
#if !defined(LUA_USE_C89)
    if (base == l_mathop(2.0))
      res = l_mathop(log2)(x);
    else
#endif
        if (base == l_mathop(10.0))
      res = l_mathop(log10)(x);
    else
      res = l_mathop(log)(x) / l_mathop(log)(base);
  }
  lua_pushnumber(L, res);
  return 1;
}

static int math_exp(lua_State *L)
{
  lua_pushnumber(L, l_mathop(exp)(luaL_checknumber(L, 1)));
  return 1;
}

static int math_deg(lua_State *L)
{
  lua_pushnumber(L, luaL_checknumber(L, 1) * (l_mathop(180.0) / PI));
  return 1;
}

static int math_rad(lua_State *L)
{
  lua_pushnumber(L, luaL_checknumber(L, 1) * (PI / l_mathop(180.0)));
  return 1;
}

static int math_min(lua_State *L)
{
  int n = lua_gettop(L); /* number of arguments */
  int imin = 1;          /* index of current minimum value */
  int i;
  luaL_argcheck(L, n >= 1, 1, "value expected");
  for (i = 2; i <= n; i++)
  {
    if (lua_compare(L, i, imin, LUA_OPLT))
      imin = i;
  }
  lua_pushvalue(L, imin);
  return 1;
}

static int math_max(lua_State *L)
{
  int n = lua_gettop(L); /* number of arguments */
  int imax = 1;          /* index of current maximum value */
  int i;
  luaL_argcheck(L, n >= 1, 1, "value expected");
  for (i = 2; i <= n; i++)
  {
    if (lua_compare(L, imax, i, LUA_OPLT))
      imax = i;
  }
  lua_pushvalue(L, imax);
  return 1;
}

/*
** This function uses 'double' (instead of 'lua_Number') to ensure that
** all bits from 'l_rand' can be represented, and that 'RANDMAX + 1.0'
** will keep full precision (ensuring that 'r' is always less than 1.0.)
*/
static int math_random(lua_State *L)
{
  lua_Integer low, up;
  double r = (double)l_rand() * (1.0 / ((double)L_RANDMAX + 1.0));
  switch (lua_gettop(L))
  { /* check number of arguments */
  case 0:
  {                                   /* no arguments */
    lua_pushnumber(L, (lua_Number)r); /* Number between 0 and 1 */
    return 1;
  }
  case 1:
  { /* only upper limit */
    low = 1;
    up = luaL_checkinteger(L, 1);
    break;
  }
  case 2:
  { /* lower and upper limits */
    low = luaL_checkinteger(L, 1);
    up = luaL_checkinteger(L, 2);
    break;
  }
  default:
    return luaL_error(L, "wrong number of arguments");
  }
  /* random integer in the interval [low, up] */
  luaL_argcheck(L, low <= up, 1, "interval is empty");
  luaL_argcheck(L, low >= 0 || up <= LUA_MAXINTEGER + low, 1,
                "interval too large");
  r *= (double)(up - low) + 1.0;
  lua_pushinteger(L, (lua_Integer)r + low);
  return 1;
}

static int math_randomseed(lua_State *L)
{
  l_srand((unsigned int)(lua_Integer)luaL_checknumber(L, 1));
  (void)l_rand(); /* discard first value to avoid undesirable correlations */
  return 0;
}

static int math_type(lua_State *L)
{
  if (lua_type(L, 1) == LUA_TNUMBER)
  {
    if (lua_isinteger(L, 1))
      lua_pushliteral(L, "integer");
    else
      lua_pushliteral(L, "float");
  }
  else
  {
    luaL_checkany(L, 1);
    lua_pushnil(L);
  }
  return 1;
}

/*
** {==================================================================
** Deprecated functions (for compatibility only)
** ===================================================================
*/
#if defined(LUA_COMPAT_MATHLIB)

static int math_cosh(lua_State *L)
{
  lua_pushnumber(L, l_mathop(cosh)(luaL_checknumber(L, 1)));
  return 1;
}

static int math_sinh(lua_State *L)
{
  lua_pushnumber(L, l_mathop(sinh)(luaL_checknumber(L, 1)));
  return 1;
}

static int math_tanh(lua_State *L)
{
  lua_pushnumber(L, l_mathop(tanh)(luaL_checknumber(L, 1)));
  return 1;
}

static int math_pow(lua_State *L)
{
  lua_Number x = luaL_checknumber(L, 1);
  lua_Number y = luaL_checknumber(L, 2);
  lua_pushnumber(L, l_mathop(pow)(x, y));
  return 1;
}

static int math_frexp(lua_State *L)
{
  int e;
  lua_pushnumber(L, l_mathop(frexp)(luaL_checknumber(L, 1), &e));
  lua_pushinteger(L, e);
  return 2;
}

static int math_ldexp(lua_State *L)
{
  lua_Number x = luaL_checknumber(L, 1);
  int ep = (int)luaL_checkinteger(L, 2);
  lua_pushnumber(L, l_mathop(ldexp)(x, ep));
  return 1;
}

static int math_log10(lua_State *L)
{
  lua_pushnumber(L, l_mathop(log10)(luaL_checknumber(L, 1)));
  return 1;
}

#endif
/* }================================================================== */

static const luaL_Reg mathlib[] = {
    {"abs", math_abs},
    {"acos", math_acos},
    {"asin", math_asin},
    {"atan", math_atan},
    {"ceil", math_ceil},
    {"cos", math_cos},
    {"deg", math_deg},
    {"exp", math_exp},
    {"tointeger", math_toint},
    {"floor", math_floor},
    {"fmod", math_fmod},
    {"ult", math_ult},
    {"log", math_log},
    {"max", math_max},
    {"min", math_min},
    {"modf", math_modf},
    {"rad", math_rad},
    {"random", math_random},
    {"randomseed", math_randomseed},
    {"sin", math_sin},
    {"sqrt", math_sqrt},
    {"tan", math_tan},
    {"type", math_type},
#if defined(LUA_COMPAT_MATHLIB)
    {"atan2", math_atan},
    {"cosh", math_cosh},
    {"sinh", math_sinh},
    {"tanh", math_tanh},
    {"pow", math_pow},
    {"frexp", math_frexp},
    {"ldexp", math_ldexp},
    {"log10", math_log10},
#endif
    /* placeholders */
    {"pi", NULL},
    {"huge", NULL},
    {"maxinteger", NULL},
    {"mininteger", NULL},
    {NULL, NULL}};

/*
** Open math library
*/
LUAMOD_API int luaopen_math(lua_State *L)
{
  luaL_newlib(L, mathlib);
  lua_pushnumber(L, PI);
  lua_setfield(L, -2, "pi");
  lua_pushnumber(L, (lua_Number)HUGE_VAL);
  lua_setfield(L, -2, "huge");
  lua_pushinteger(L, LUA_MAXINTEGER);
  lua_setfield(L, -2, "maxinteger");
  lua_pushinteger(L, LUA_MININTEGER);
  lua_setfield(L, -2, "mininteger");
  return 1;
}
